I'm aware of a number of schemes to concentrate a magnetic field inside an area. Most obviously, the total field strength inside a solenoid is much greater than the total field strength outside of it. Is the reverse possible?
closed as unclear what you're asking by Yashas, Jon Custer, ZeroTheHero, John Rennie, Danu Apr 23 '17 at 8:43
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Consider a hollow cylinder with current running along it. The inside has no magnetic field but the outside has magnetic field.